Ingram Publishing/Thinkstock(WAUKESHA, Wis.) — A judge on Wednesday granted a competency evaluation for one of the two 12-year-old girls charged in the Slender Man stabbing, but it’s still unclear whether the preteens will be tried as juveniles or adults.

Under Wisconsin law, adult courts get jurisdiction over children who have been charged with attempted homicide if they are 10 years old or older. But a lawyer may ask to move the two 12-year-old girls charged with stabbing their friend 19 times to please “Slender Man” to juvenile court.

So what’s the difference between a 10-year-old’s brain and a 12-year-old’s brain? It depends on the individual child, experts said.

“The bottom line is that we’re still dealing with an immature brain,” Dr. Max Wiznitzer, a pediatric neurologist at UH Rainbow Babies & Children’s Hospital in Cleveland.

Morgan Geyser and Anissa Weier of Waukesha County, Wisconsin, were charged with attempted first-degree intentional homicide. They allegedly lured their friend into the woods and then stabbed her 19 times on May 31 in the hopes of meeting “Slender Man,” a popular fictional character on the Internet that has no face and hunts children.

Children younger than 10 years old are more likely to “have unrealistic expectations of their surroundings” and engage in “fantasy play” than preteens, said Dr. Bradley Freeman, a psychology professor at Vanderbilt University in Tennessee.

“We all know that little kids have that magical thinking where Superman exists and people can fly around the world and things like that,” he said. “Those types of thoughts, that type of magical thinking, that tends to disappear around the ages of 8 to 10 years old.”

Although this seems to fit into the Wisconsin law, which states a child is to be tried in adult court if he or she attempted to commit murder “on or after the juvenile’s 10th birthday,” Freeman said not all children mature at the same pace.

“Courts have a difficult time parsing that out because things have to be black and white,” he said. “That type of regulation totally omits the idea that people can be at different levels of maturation even at the same age.”

Freeman said adult courts tend to be more punitive, while juvenile courts tend to be more rehabilitative, which means that the 12-year-olds may not get the help they need if they’re found to have mental illness and tried in adult court.

“That’s the crux of the issue really,” Freeman said.

Wiznitzer said the brain undergoes “incremental” changes between 10 and 12 years old as white and gray matter increase and nerves learn to communicate more efficiently, but the brain is not fully developed until a person reaches their mid-20s.

Freeman added that the frontal lobe of the brain, which controls rational thinking and common sense, does not fully develop until someone is in his or her early 20s. This is why people into their late teens tend to engage in risky behavior, such as speeding, he said.